The Gordian knot of the Middle East conflict will probably be solved long before humans manage to overcome head lice, which infest the scalps of 70 percent of all children at least once in their lives and are currently ensconced on the heads of 15% of those aged four to 13, who are due to start school next week. Dr. Kosta Mumcuoglu, a senior research associate and leading parasitology expert at the Hebrew University-Hadassah Medical School's Kuvin Center for Infectious and Tropical Diseases, has been fighting head lice for 25 years, examining the heads of thousands of infested children around the country, especially in the Jerusalem area, and providing parents with preparations to kill the lice. He sometimes also literally takes his work home with him, as some lice hitchhike on his own head. Parents are instructed to go over their children's heads with a fine-toothed metal comb, apply cream rinse to eliminate tangles and curls, and then use the preparation according to his instructions. Hedrin (dimeticone 4% lotion or spray), a new silicone-based product now sold in Israel, is widely regarded as the most effective lice treatment to date, but Mumcuoglu - Israel's top pediculosis expert - cautions that a second application must be done 10 days after the first for optimal results. The Health Ministry also requires periodic testing by an expert to determine whether products are still effective or whether the new generation of head lice have developed genetic changes and resistance to them. Mumcuoglu is usually the parasitologist commissioned for this research. "Even with dimeticone, there is no chance that I will be out of a job before retirement," joked Mumcuoglu, who has four grown children and stepchildren as well as six young grandchildren, most of whom have needed his treatment. Lice will live on, but he also performs maggot therapy on wounds that fail to heal and does research on ticks. Lice make their presence felt only a month or two after they arrive. The sign is pruritus, or itching, that makes their bearers scratch. The tiny male or female louse - Mumcuoglu says he can tell them apart "in his sleep" because of different-shaped sex organs visible under a microscope - bites and injects its saliva into the scalp. This saliva contains anticoagulants to keep the blood running. As head lice live solely on blood, they are forced to be draculas their whole lives. If those who scratch have bacteria and other dirt under their fingernails, they may infect the open bite holes on their scalps, but secondary infections rarely occur. Lice are almost always unpleasant, but not dangerous, he declared. Many American children who have only empty eggs (nits) on their hair or scalp - especially at the nape of their necks or behind their ears - are routinely sent home with a note to their parents. Mumcuoglu absolutely opposes this policy not only because nits are not alive and cause no harm, but also due to the psychological damage it can do to kids. "This is not done in Israel," he said. "I have written articles criticizing the US practice, and I hope the Americans are beginning to take notice and will abolish it." He noted that pediculosis infest children throughout the world, including rich countries like the US and Europe, but they seem more pervasive in Israel where families are generally larger. A major reason for the higher pediculosis rate in Israel is that for years ineffective pediculocides were used, leading to resistance. In addition, "in the US there are school nurses everywhere. Today, there are many fewer nurses here, and they mostly just give vaccinations. They are no longer responsible for diagnosis of pediculosis. And even if they do look for them, most do not have time or know how to do it right; they see lifeless nits on the nape and behind the ears and mistakenly think they are live eggs." In the end, the burden falls mostly on mothers at home. Adults can also be infested with the bugs by children, said Mumcuoglu, but lice prefer "young blood" over older blood, even if heads touch, because of hormones or unknown factors that deter the bugs. Head lice do not compete with body lice or pubic lice, he says. Each type protect their own geographical territory, and they are treated differently; some 40,000 pubic-hair treatments are still purchased annually in Israel, but there are almost no body lice, which infest clothing. The only way to prevent head lice completely is to shave your head, Mumcuoglu pointed out. "That is probably why monks in the Far East have none." In the 1950s and 1960s in the West, pediculosis was rare because DDT was used after World War II. But its use was discontinued due to the pesticide's dangers to health. Then, lice on the heads of poor children spread to the (usually clean) heads of middle-class and wealthy children - even to the sons of England's Prince Charles. Lice apparently "prefer" clean, shampooed hair, said the parasitologist, because there are no barriers, but they have a lower chance of survival, as careful combing breaks the lice's legs. Girls are more likely to be infested than boys with short haircuts, and those with curly, tangled hair are at higher risk because they are harder to treat. Girls with long hair are advised to put it into a closed bun on the top of their heads, but a pony tail is better than leaving hair free. Permethrin - a pesticide that used to be quite effective in shampoo form against lice - is rarely used today, due to resistance by the lice. Pesticide preparations based on malathion and carbaryl and a natural product combining anise, coconut and ylangylang, also kill lice for the time being. But dimeticone, as well as isopropyl myristat that also suffocates and dries lice, is a new generation of effective pediculocides if used properly. The second application of all these preparations must be no earlier than 10 days after the first. He urges parents to check kids' heads once a week with a fine-toothed comb and when infestation recurs, they are advised to rub into the whole scalp every morning a few drops of rosemary oil that most lice can't stand. But it seems that few parents and kids have time to do this on a daily basis. Neither do they have much patience for Robicombi, a fine-toothed comb with a weak electrical current running through it that electrocutes the lice (but not the child). It works better on short-to-medium and straight to wavy hair. However, it does not destroy the eggs, so the treatment must be repeated every day or two for 10 days and reused frequently to prevent reinfestation. "The quicker the diagnosis, the easier the treatment. So weekly examination is recommended, especially for those with chronic pediculosis," he said. "If parents use the most effective preparation according to my guidelines, apply cream rinse and comb the hair regularly (ideally, each child should have his own comb) and try to deter lice with rosemary oil, they will probably be able to defeat them without any outsider's help," Mumcuoglu concludes.